Semiconductor device package with warpage control structure

ABSTRACT

Between an adhesive surface of a heat spreader lid and a top surface of a semiconductor package, in addition to a spreader adhesive layer, several warpage control adhesive layers are also provided. The warpage control adhesive layers are disposed on corner areas of the adhesive surface of the heat spreader lid to reduce high temperature warpage of the semiconductor device package.

BACKGROUND

In semiconductor device package assembly, a semiconductor die (also referred to as an integrated circuit (IC) chip or “chip”) may be bonded directly to a packaging substrate. Such die is formed with bumps of solder affixed to its I/O bonding pads. During packaging, the die is “flipped” onto its front surface (e.g., active circuit surface) so that the solder bumps form electrical and mechanical connections directly between the die and conductive metal pads on the packaging substrate. Underfill is generally applied between the gap formed by the solder bumps in order to further secure the die to the packaging substrate. A semiconductor device package of this type is commonly called a “flip chip package.”

In addition, a heat spreader may further attached over the die and packaging substrate to enhance the heat dissipation ability of the flip chip package. A problem with such a flip chip package is that it is subject to different temperatures during the packaging process. For instance, different temperatures arise with the cool down from the solder joining temperature and the underfill curing temperature. As a result, the package is highly stressed due to the different coefficients of thermal expansion (CTE) of the various package and die materials. The high stress experienced by bonded materials during heating and cooling may cause them to warp or crack and cause the package structure to bow.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1A is a top view diagram of a semiconductor device package with a warpage control structure according some embodiments in this disclosure.

FIGS. 1B and 1C are cross-sectional diagrams of cutting line BC in FIG. 1A.

FIG. 2A is a table listing simulation results of warpage of a semiconductor device package with a heat spreader lid at 260° C. by finite element analysis.

FIG. 2B is a cross-sectional diagram of a warped semiconductor device package with a crying warpage.

The drawings, schematics and diagrams are illustrative and not intended to be limiting, but are examples of embodiments of the disclosure, are simplified for explanatory purposes, and are not drawn to scale.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

It was found that when a flip-chip chip scale package (fcCSP) without attaching a heat spreader lid, a smiling type warpage of the fcCSP was occurred at a high temperature. After attaching a heat spreader lid, the smile warpage of the fcCSP at the high temperature was changed to crying warpage at the high temperature, and the warpage was enlarged. Therefore, the bridging percentage of the BGA balls at the peripheral area of the fcCSP was increased by this enlarged crying warpage.

Accordingly, in some embodiments, a semiconductor device package with a warpage control structure is provided in this disclosure to reduce the high stress experienced by bonded various materials in the semiconductor device package during cycles of heating and cooling. FIG. 1A is a top view diagram of a semiconductor device package with a warpage control structure according some embodiments in this disclosure. FIG. 1B or FIG. 1C is a cross-sectional diagram of cutting line BC in FIG. 1A. Accordingly, FIGS. 1A-1C are referred below at the same time.

In a semiconductor device package shown FIGS. 1A-1C, a substrate 110 has a board surface 112 and a die surface 114. On the board surface 112 of the substrate 110, ball grid array (BGA) connectors 116 are disposed for connecting a printed circuit board (not shown in FIGS. 1A-1C).

In some embodiments, the substrate 110 above may be a semiconductor wafer, or a portion of a wafer. The wafer may be silicon, gallium arsenide, silicon on insulator (“SOT”) or other similar materials. The wafer may include passive devices such as resistors, capacitors, inductors and the like, or active devices such as transistors. The wafer may also include additional integrated circuits. In some other embodiments, the substrate 110 may be made from some other materials, such as a multiple layer circuit boards made from a bismaleimide-triazine resin (such as a BT-epoxy resin) or glass-reinforced epoxy laminated sheets, for example.

At least one die 120 may be disposed on the die surface 114 of the substrate 110. The die 120 has an active circuit surface 122 and an inactive surface 124. Some solder bumps 126 are disposed on the active circuit surface 122 of the die 120. The die 120 and the substrate 110 are electrically connected by the solder bumps 126.

The solder material of the solder bumps 126 may be lead based or lead free, such as silver, copper, or tin-based compositions. The material of the solder bumps 126 will be eutectics with a common melting point for use in a reflow process. The solder bumps 126 can be plated using electro or electroless plating techniques, or may be formed using screening or jet printing techniques. The solder bumps 126 also may be other types of connectors, such as copper or gold pillars, conductive studs, or C4 columns.

Next, an underfill 130 may be used to mechanically reinforce the connection between the die 120 and the substrate 110. The underfill 130 may be made from a thermoset epoxy resin, which is dispensed into the remaining space (or “gap”) between the die 120 and the substrate 110 by a capillary underfill process, for example. The underfill 130 is then cured by heating.

In addition, a molding layer 132 b in FIG. 1B can be formed to surround the lateral side of the die 120 to further enhance the mechanical bonding strength between the die 120 and the substrate 110 in some embodiments. In FIG. 1B, the exposed inactive surface 124 of the die 120 and the top surface 134 b of the molding layer 132 b compose a substantial planar top surface.

Alternatively, a molding layer 132 c in FIG. 1C also can be formed to surround the lateral side of the die 120 and cover the inactive surface 124 of the die 120 by overmolding process to further enhance the mechanical bonding strength between the die 120 and the substrate 110 in some other embodiments. In FIG. 1C, the top surface 134 c of the molding layer 132 c is substantial planar.

The molding layer 132 b or the molding layer 132 c may be made from a composite material comprises a thermoset epoxy resin (such as bisphenol-A epoxy or Novolac™ epoxy) and a filler (such as silica, alumina or glass fillers) for adjusting a thermal expansion coefficient and elasticity of the composite material. In some embodiments, the content of thermoset epoxy resin may be 25-35 wt %, and the content of the filler may be 65-73 wt %.

Furthermore, a molding underfill process may be used in some other embodiments. Thus, the underfill 130 as well as the molding layer 132 b or the molding layer 132 c may be formed by one compound material by the molding underfill process.

A sheet of heat spreader lid 150 is further disposed on the top surface of the semiconductor device package, i.e. the top surface composed by the top surface 134 b of the molding layer 132 b and the inactive surface 124 of the die 120 in FIG. 1B, or the top surface 134 c of the molding layer 132 c in FIG. 1C. The heat spreader lid 150 has an adhesive surface 152, which is substantially planar and faces the top surface of the semiconductor device package described above.

A spreader adhesive layer 140 is disposed between the top surface of the semiconductor device package, as described above, and the adhesive surface 152 of the heat spreader lid 150. The spreader adhesive layer 140 is located on a central area of the adhesive surface 152 of the heat spreader lid 150 (see FIG. 1A) to fix the heat spreader lid 150 onto the top surface of the semiconductor device package.

Since the spreader adhesive layer 140 is responsible to attach the heat spreader lid 150 on to the semiconductor device package, the coverage of the spreader adhesive layer 140 on the adhesive surface 152 of the heat spreader lid 150 cannot be too small. In some embodiments, the coverage of the spreader adhesive layer 140 on the adhesive surface 152 of the heat spreader lid 150 is at least 30%. Oppositely, if the coverage of the spreader adhesive layer 140 on the adhesive surface 152 of the heat spreader lid 150 is too much, problems of glue overflowing and warpage may occur. Therefore, in some embodiments, the coverage of the spreader adhesive layer 140 on the adhesive surface 152 of the heat spreader lid 150 may be at most 80%. Accordingly, In some embodiments, the spreader adhesive 140 covers about 30% to about 80%, such as 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%, of the adhesive surface 152. In some other embodiments, the spreader adhesive 140 covers about 40% to about 80% of the adhesive surface 152. In some other embodiments, the spreader adhesive 140 covers about 40% to about 75% of the adhesive surface 152.

In addition, several warpage control adhesive layers 142 are disposed on corner areas of the adhesive surface 152 of the heat spreader lid 150 (see FIG. 1A). The warpage control adhesive layers 142 are separated from the spreader adhesive layer 140 by a distance d. In some embodiments, the distance d may be at least 1 mm. In some other embodiments, the area of the warpage control adhesive layers 142 each may be from about 0.5 mm² to about 100 mm². In some other embodiments, the shape of the warpage control adhesive layers 142 each may be any useful shapes, such as circle, oval, rectangular, donut, or an irregular shape. In some other embodiments, the number of the warpage control adhesive layers 142 disposed on each corner area may be one or more. In some other embodiments, the warpage control adhesive layers 142 may be made from a solder, a resin, or a glue.

Some simulations were done for the pattern composed by the spreader adhesive layer 140 and the warpage control adhesive layers 142 by finite element analysis (FEA) to predict the warpage of the semiconductor device package with a heat spreader lid at 260° C., which is a reflow temperature of the BGA balls. The obtained results are listed in a table shown in FIG. 2A.

FIG. 2B is a cross-sectional diagram of a warped semiconductor device package with a crying warpage. In FIG. 2B, the warped semiconductor device package includes a substrate 210 with BGA balls 216, a die 220 with solder bumps 226, an underfill 230, a molding layer 232, a spreader adhesive layer 240 and a heat spreader lid 250. The warpage w is defined by the level difference between the highest BGA ball 216 a and the lowest BGA ball 216 b. Accordingly, in the table of FIG. 2A, the predicted warpage at 260° C. of a semiconductor device package with 100% coverage of the spreader adhesive layer (i.e. example CE1) is normalized to 1.00.

In the table of FIG. 2, the coverage of the spreader adhesive layer on the adhesive surface of a heat spreader lid was varied from 100% to 50% for CE1 to CE4. Along with the decrease of the coverage of the spreader adhesive layer 240 on the adhesive surface of a heat spreader lid, the predicted warpage of the fcCSP at 260° C. was varied from 1.00, 1.11, 1.06, to 0.92. it seems that the decrease of the spreader adhesive layer's coverage can slightly decrease the warpage of the semiconductor device package.

In examples CE5 and CE6, the coverage of the spreader adhesive layer 240 was maintained at 50%, but the corners of the spreader adhesive layer have some extensions 241 extending respectively toward to the corners of the heat spreader lid. The coverage of the extension 241 of CE6 is more than CE5, and the predicted warpage of the CE6 is less than CE5 (0.89 v. 1.00).

Surprisingly, in examples E1 to E3, after the extensions 241 of the spreader adhesive layer 240 in examples CE5 and CE6 were separated from the spreader adhesive layer 240 to form warpage control adhesive layers 242, the predicted warpage can be further decreased (0.81 to 0.87). Therefore, it can be known that the warpage control adhesive layers, which are separated from the spreader adhesive layer, can effectively decrease the predicted warpage of a semiconductor device package at high temperature to effectively decrease bridging percentage of BGA connectors of the semiconductor device package, and the yield can thus be improved as well.

Accordingly, in some embodiments, a warpage control structure of a semiconductor device package with a heat spreader lid is provided. The warpage control structure comprises a plurality of warpage control adhesive layers disposed between a top surface of a molding layer and an adhesive surface of a heat spreader lid as well as on plural corner areas of the adhesive surface of the heat spreader lid. The top surface of the molding layer and the adhesive surface of the heat spreader lid are substantial planar.

In some other embodiments, a warpage control pattern of adhesive layers for attaching an adhesive surface of a heat spreader lid to a top surface of a semiconductor device package is provided. The top surface of the semiconductor device package and the adhesive surface of the heat spreader lid are substantial planar. The warpage control pattern comprises a spreader adhesive layer disposed on a central area of the adhesive surface of the heat spreader lid, and a plurality of warpage control adhesive layers respectively disposed on plural corner areas of the adhesive surface of the heat spreader lid and disposed to be separated from the spreader adhesive layer.

In some other embodiments, a semiconductor device package with a heat spreader lid is also provided. The semiconductor device package comprises a substrate, a die, a molding layer, a heat spreader lid, a spreader adhesive layer, and a plurality of warpage control adhesive layers. The substrate has a die surface and a board surface. The die has an active circuit surface and an inactive surface, and the active circuit surface of the die is electrically and mechanically coupled to the die surface of the substrate. The molding layer is disposed to fill a space above the die surface of the substrate. The molding layer or the molding layer and the inactive surface compose a substantial planar top surface. The heat spreader lid is disposed above the molding layer, wherein the heat spreader lid has a substantial planar adhesive surface. The spreader adhesive layer is disposed between the substantial planar top surface and a central area of the adhesive surface of the heat spreader lid. The warpage control adhesive layers are disposed between the top surface and on plural corner areas of the adhesive surface of the heat spreader lid, and the warpage control adhesive layers are separated from the spreader adhesive layer.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A warpage control structure of a semiconductor device package with a heat spreader lid, the warpage control structure comprising: a plurality of warpage control adhesive layers disposed between a top surface of a molding layer and an adhesive surface of the heat spreader lid as well as on plural corner areas of the adhesive surface of the heat spreader lid, wherein the top surface of the molding layer and the adhesive surface of the heat spreader lid are substantial planar, and a spacing in a direction parallel with the top surface of the molding layer is present between at least one of the warpage control adhesive layers and a die surrounded by the molding layer; and a spreader adhesive layer disposed on a central area of the adhesive surface of the heat spreader lid and covering about 30% to about 80% of the adhesive surface of the heat spreader lid, the spreader adhesive layer being over the die.
 2. The warpage control structure of claim 1, wherein the warpage control adhesive layers are separated from the spreader adhesive layer by at least 1 mm.
 3. The warpage control structure of claim 1, wherein an area of the warpage control adhesive layers is from about 0.5 mm² to about 100 mm².
 4. The warpage control structure of claim 1, wherein the warpage control adhesive layers is made from a solder, a resin, or a glue.
 5. The warpage control structure of claim 1, wherein a shape of the warpage control adhesive layers is circle, oval, rectangular, donut, or an irregular shape.
 6. The warpage control structure of claim 1, wherein a number of the warpage control adhesive layers disposed on each corner area is one or more.
 7. The warpage control structure of claim 1, wherein the molding layer is made from a composite material comprising a thermoset epoxy resin and a filler.
 8. The warpage control structure of claim 7, wherein a content of the thermoset epoxy resin is 25-35 wt %.
 9. The warpage control structure of claim 7, wherein a content of the filler is 65-73 wt %.
 10. The warpage control structure of claim 7, wherein the thermoset epoxy resin is bisphenol-A epoxy.
 11. The warpage control structure of claim 7, wherein the filler is a silica filler, an alumina filler or a glass filler.
 12. The warpage control structure of claim 1, wherein an inactive surface of the die and the top surface of the molding layer compose a substantial planar top surface.
 13. The warpage control structure of claim 1, wherein the die is disposed on a substrate.
 14. The warpage control structure of claim 13, wherein the substrate is a semiconductor wafer or a portion of a wafer.
 15. The warpage control structure of claim 1, wherein the spreader adhesive layer covers about 50% of the adhesive surface of the heat spreader lid.
 16. The warpage control structure of claim 13, wherein the die and the substrate are electrically connected by a solder bump.
 17. A warpage control structure of a semiconductor device package with a heat spreader lid, the warpage control structure comprising: a warpage control adhesive layer between a top surface of a molding layer and an adhesive surface of the heat spreader lid, wherein a die surrounded by the molding layer is free from coverage by the warpage control adhesive layer; and a spreader adhesive layer over the die.
 18. The warpage control structure of claim 17, wherein the spreader adhesive layer has a border substantially aligned with an outer edge of the die.
 19. A warpage control structure of a semiconductor device package with a heat spreader lid, the warpage control structure comprising: a warpage control adhesive layer between a top surface of a molding layer and an adhesive surface of the heat spreader lid, wherein a spacing in a direction parallel with the top surface of the molding layer is present between the warpage control adhesive layer and a die surrounded by the molding layer; and a spreader adhesive layer between the die and the adhesive surface of the heat spreader lid.
 20. The warpage control structure of claim 19, wherein an inactive surface of the die is substantially coplanar with the top surface of the molding layer. 